装配式轻钢框架-轻钢桁架结构振动台试验研究

Shaking table test on prefabricated light steel frame with light steel truss structure

摘要:

为研究装配式轻钢框架-轻钢桁架结构的抗震性能及桁架式“L”形柱的震坏机理,进行了一座两层房屋的足尺模型振动台试验.对模型进行42个工况的地震波输入,运用模态分析理论识别了模型结构的动力特性,分析了加速度响应、位移响应和应变响应的变化规律.研究表明:在地震波加速度峰值从0.07g逐渐增大到0.9g的过程中,结构自振频率逐步下降；加速度放大系数逐渐降低；最大层间位移出现在首层,在8度基本地震动和8度罕遇地震动时的最大层间位移角分别为1/268和1/164,低于多层钢结构的弹性层间位移角限值和弹塑性层间位移角限值；结构能满足“两阶段、三水准”的抗震设防要求.模型中的桁架式“L”形柱在8度基本地震动时处于弹性状态,在8度罕遇地震动时有部分桁架节点处焊缝开裂并进入塑性状态,在9度罕遇地震动时结构塑性变形加大但仍有一定安全储备,在9度极罕遇地震动时刚度严重退化.结构在经历了渐进的塑性变形过程后,仍保持一定的承载能力,具有较好的延性,可在高设防烈度地区应用.

Abstract:

In order to study the aseismic performance of prefabricated light steel frame with light steel truss structure and the seismic failure mechanism of truss-type L-shaped column, full-scale shaking table tests were performed on a two-story building model. Seismic waves in 42 events were input to model structure. The dynamic properties of model structure was quantified by model analysis theories. The change regularity of acceleration responses, displacement responses, and strain responses were analyzed. Results show that with the peak acceleration of seismic waves increasing from 0.07g to 0.9g, both the fundamental frequency and the acceleration magnification factor of the structure decreased gradually. The maximum inter-story drift occurred in the first floor, and the maximum inter-story drift ratios under basis ground motion and rare ground motion of 8-degree was 1/268 and 1/164, respectively, which were lower than the elastic and elastic-plastic inter-story drift ratio limits of multistory steel structure. The model structure can basically satisfy the two-phase and three-level seismic fortification requirements. The truss-type L-shaped column in the model was in elastic state under basis ground motion of 8 degree. Crack was found at the junctions between end column and diagonal member under rare ground motion of 8 degree. At the same time, the L-shaped column enter plastic stage, although the plastic drift increased under rare ground motion of 9 degree and a certain safety margin was remained. The lateral stiffness of L-shaped column degraded severely under very rare ground motion of 9 degree. After the gradual process of plastic deformation, the L-shaped column retained a certain level of carrying capacity, so it has good ductility and can be used in seismic fortification region of high degree.